Use alkali and/or triethanolamine salts of the alkanoylamidocarboxylic acids in metal working

ABSTRACT

At least 5, preferably at least 30, in particular about 50, percent by weight of the alkali metal salts and/or triethanolamine salts of alkanoylamidocarboxylic acids of the general formula ##STR1## R 1  denotes an alkanoyl or an alkanesulfonyl radical, each having 6 to 20 carbon atoms, ##STR2## R 4  denotes a hydrogen atom; m is 2; 
     n is 0 or 1, and 
     z denotes an integer from 0 to 3; 
     are used as antifoams in corrosion-inhibiting metal working compositions.

The invention relates to alkali metal salts and triethanolamine salts ofalkanoylamidocarboxylic acids, as have been disclosed as metal workingcompositions in AT 344 854 B. According to said publication, such saltshave been used to date as corrosion-inhibiting coolants and metalworking compositions. Most salts stated there gave good to very goodcorrosion protection in the machining of the workpieces. However, theyexhibit undesirably strong foaming in modern high-speed metal workingcentres, owing to the large cooling lubricant circulation and the highdelivery pressure. The addition of commercial antifoams results in onlya partial improvement and in particular only briefly, and on the otherhand occasionally gives rise to undesired side effects.

It is therefore the object of the invention to select those salts whichexhibit a continuously low level of foaming behaviour which meets therequirements of modern NC machines. This is achieved in a surprisingmanner by alkali metal salts and/or triethanolamine salts ofalkanoylamidocarboxylic acids of the general formula (A) ##STR3## inwhich R¹ denotes an alkanoyl or an alkanesulfonyl radical, each having 6to 20 carbon atoms;

R² denotes the radical ##STR4## R³ denotes the radical R² or ##STR5## R⁴denotes a hydrogen atom or an alkane radical having 1 to 3 carbon atoms;

m is 2

n is 0 or 1, and

z denotes an integer form 0-3

in an amount of at least 5, preferably at least 30, in particular 50,percent by weight of the concentrate of corrosion-inhibiting metalworking compositions in aqueous solution, as antifoams.

They include virtually exclusively salts ofmonoalkanoylethylenediaminetriacetic ormonoalkanoylethylenediaminetripropionic acids,monoalkanoyldiethylenetriaminetetraacetic ormonoalkanoyldiethylenetriaminetetrapropionic acids,monoalkanoyltriethylenetetraminepentaacetic ormonoalkanoyltriethylenetetraminepentapropionic acids ormonoalkanoyltetraethylenepentaminehexaacetic ormonoalkanoyltetraethylenepentaminehexapropionic acids, i.e.:

1. N-caproylethylenediamine-N,N',N'-triacetic acid

2. N-caproylethylenediamine-N,N',N'-tripropionic acid

3. N-isooctanoylethylenediamine-N,N',N'-triacetic acid

4. N-isooctanoylethylenediamine-N,N',N'-tripropionic acid

5. N-isononanoylethylenediamine-N,N',N'-triacetic acid

6. N-isononanoylethylenediamine-N,N',N'-tripropionic acid

7. N-isononanoyldiethylenetriamine-N,N',N",N"-tetraacetic acid

8. N-isononanoyldiethylenetriamine-N,N',N",N"-tetrapropionic acid

9. N-decanoylethylenediamine-N,N',N'-triacetic acid

10. N-decanoylethylenediamine-N,N',N'-tripropionic acid

11. N-undecanoylethylenediamine-N,N',N'-triacetic acid

12. N-undecanoylethylenediamine-N,N',N'-tripropionic acid

In 2% aqueous solution, salts of these acids give such low-foam coolinglubricants that they no longer give rise to any troublesome foamdevelopment even with the largest cooling lubricant circulation anddelivery pressures up to 20 bar.

The foam behaviour of the above-mentioned compounds was now tested bythe perforated-disc beating method according to DIN 53902, Part 1,compounds of the Austrian Patent mentioned at the outset, namely thetriethanolamine salts of N,N'-diisononanoylethylenediamine-N,N'-diaceticacid (A) or of N,N'-diisononanoylethylenediamine-N,N'-dipropionic acid(B), exhibiting very disadvantageous foaming behaviour.

                                      TABLE 1                                     __________________________________________________________________________    Triethanol-    Foam height                                                                             Foam height                                                                         Foam height                                                                         Foam height                              amine salt of                                                                        Concentration                                                                         (in mm) immediately                                                                     (in mm)                                                                             (in mm)                                                                             (in mm)                                  compound No.                                                                         (in % by weight)                                                                      after beating                                                                           after 10 sec                                                                        after 20 sec                                                                        after 30 sec                             __________________________________________________________________________    Blank  distilled                                                                             10        0     0     0                                        sample water                                                                  A      2%      100       70    58    40                                       B      2%      105       72    60    41                                       1      2%      13        2     0     0                                        2      2%      15        1     0     0                                        3      2%      15        2     0     0                                        4      2%      15        1     0     0                                        5      2%      15        2     0     0                                        6      2%      15        2     0     0                                        7      2%      12        0     0     0                                        8      2%      13        0     0     0                                        9      2%      16        3     0     0                                        10     2%      16        2     0     0                                        11     2%      17        4     0     0                                        12     2%      17        4     0     0                                        __________________________________________________________________________

As shown in Table 1, for example A gave a foam height of 100 mmimmediately after beating, which was still 70 mm after 10 sec, 58 mmafter 20 sec and declined to 7 mm only after 180 sec. In contrast, thecompounds according to the invention exhibited a substantially moreadvantageous foam behaviour.

Interestingly, the foam effect of other salts, in particular of thosesalts protected in the Austrian Patent mentioned at the outset, but alsoof those other, conventional, water-miscible cooling lubricants andmetal working compositions, for example also of oil emulsions, isgreatly reduced merely by adding small amounts of only 5 to 40,preferably 10 to 30, % by weight of the compounds according to theinvention. With additions of 50% or more, the foam effect is alreadyvirtually just as small as in the case of the pure substances accordingto the invention.

The foam behaviour of mixtures of the triethanolamine salts of the acidsaccording to the invention with other cooling lubricants, such as, forexample, A or B from the AT-patent mentioned at the outset, or withSyntelo® (from Castrol) or a mineral oil emulsion Mobilmet® 151(containing phosphoric esters and alkanolamine esters of boric acid), isshown in Table 2 below.

                                      TABLE 2                                     __________________________________________________________________________    Foam height (in mm) after beating:                                            Triethanol-                                                                   amine salts of                                                                compound No.                                                                  as a mixture with                                                                     Concentration                                                                        Immediately                                                                         after                                                                             after                                                                             after                                                                             after                                                                             after                                                                             after                                in the ratio                                                                          (% by weight)                                                                        after beating                                                                       10 sec                                                                            20 sec                                                                            30 sec                                                                            60 sec                                                                            120 sec                                                                           180 sec                              __________________________________________________________________________    for comp.:A                                                                           2%     100   70  58  40  26  12  7                                    for comp.:B                                                                           2%     105   72  60  41  26  13  8                                    No. 6:A = 30:70                                                                       2      50    40  22  15  4   0   0                                    No. 6:A = 50:50                                                                       2      15    10  5   0   0   0   0                                    No. 6:A = 60:40                                                                       2      15    7   0   0   0   0   0                                    No. 7:B = 30:70                                                                       2      40    28  16  7   0   0   0                                    No. 7:B = 50:50                                                                       2      15    10  0   0   0   0   0                                    No. 7:B = 60:40                                                                       2      13    3   0   0   0   0   0                                                   immediately                                                                         after                                                                             after                                                                             after                                                                             after                                                                             after                                                                             after                                               after beating                                                                       60 sec                                                                            120 sec                                                                           180 sec                                                                           4 min                                                                             8 min                                                                             15 min                               C (Mobilmet ®)                                                                    3      250   200 180 150 120 50  10                                   No. 6:C = 17:83                                                                       3.6    170   120 100 80  30  6   0                                    No. 6:C = 25:75                                                                       4      120   85  40  18  0   0   0                                    No. 6:C = 33:67                                                                       4.5    100   65  22  7   0   0   0                                    No. 7:C = 17:83                                                                       3.6    160   100 90  70  20  0   0                                    No. 7:C = 25:75                                                                       4      110   70  40  15  0   0   0                                    No. 7:C = 33:67                                                                       4.5    100   48  12  0   0   0   0                                    __________________________________________________________________________

We claim:
 1. A method to reduce foaming of corrosion-inhibiting metalworking compositions, comprising the steps ofselecting at least one ofalkali metal salts and triethanolamine salts of alkanoylamidocarboxylicacids of a general formula ##STR6## R¹ denoted an alkanoyl or analkanesulfonyl radical, each having 6 to 20 carbon atoms, R² denotes theradical ##STR7## R³ denotes the radical --R² or ##STR8## R⁴ denotes ahydrogen atom; m is 2 n is 0 or 1 z denotes an integer form 0 to 3, andadding an amount of at least 5 percent by weight to a concentrate ofsaid corrosion-inhibiting metal working compositions in aqueoussolution, as antifoams.
 2. The method according to claim 1,characterized in that salts of monoalkanoylethylenediaminetriacetic ormonoalkanoylethylenediaminetripropionic acids,monoalkanoyldiethylenetriaminetetraacetic ormonoalkanoyldiethylenetriaminetetrapropionic acids,monoalkanoyltriethylenetetraminepentaacetic ormonoalkanoyltriethylenetetraminepentapropionic acids ormonoalkanoyltetraethylenepentaminehexaacetic ormonoalkanoyltetraethylenepentaminehexapropionic acids, in particular ofone of the following acids, areused:N-caproylethylenediamine-N,N',N'-triacetic acidN-caproylethylenediamine-N,N',N'-tripropionic acidN-isooctanoylethylenediamine-N,N',N'-triacetic acidN-isooctanoylethylenediamine-N,N',N'-tripropionic acidN-isononanoylethylenediamine-N,N',N'-triacetic acidN-isononanoylethylenediamine-N,N',N'-tripropionic acidN-isononanoyldiethylenetriamine-N,N',N",N"-tetraacetic acidN-isononanoyldiethylenetriamine-N,N',N",N"-tetrapropionic acidN-decanoylethylenediamine-N,N',N'-triacetic acidN-decanoylethylenediamine-N,N',N'-tripropionic acidN-undecanoylethylenediamine-N,N',N'-triacetic acidN-undecanoylethylenediamine-N,N',N'-tripropionic acid.3. 3.Water-miscible, mineral oil-containing cooling lubricants and metalworking compositions, containing 5 to 40 percent by weight of at leastone of alkali metal salts and triethanolamine salts ofalkanoylamidocarboxylic acid of a general formula ##STR9## R¹ denoted analkanoyl or an alkanesulfonyl radical, each having 6 to 20 carbonatoms,R² denotes the radical ##STR10## R³ denotes the radical --R² or##STR11## R⁴ denotes a hydrogen atom; m is 2 n is 0 or 1 z denotes aninteger form 0 to 3 in an amount of at least 5 percent by weight of aconcentrate of corrosion-inhibiting metal working compositions inaqueous solution, as antifoams.
 4. The method according to claim 1,wherein said antifoams are added in an amount of at least 30 percent byweight of a concentrate of corrosion-inhibiting metal workingcompositions in aqueous solution.
 5. The method according to claim 1,wherein said antifoams are added in an amount of at least 50 percent byweight of the concentrate of corrosion-inhibiting metal workingcompositions in aqueous solution.
 6. The water-miscible, mineraloil-containing cooling lubricants and metal working compositionsaccording to claim 3, containing 10 to 30 percent by weight of saidsalts.